San Juan Basin Royalty is an express trust created under the laws of the state of Texas by the San Juan Basin Royalty Trust Indenture. The Trustee, Bank One, Texas, N.A. , has the primary function of collecting monthly net proceeds attributable to the Royalty and making the monthly distributions to the unit holders after deducting administrative expenses and any amounts necessary for cash reserves.

To understand what a lot of these companies are, one must understand what a holding company is. A holding company does not necessarily produce anything or provide a service. Usually a "holding company" or trust will simply buy companies that are already profitable, let them run as usual, and use that profit to buy more companies. Most of the companies in this list fall into the holding company category. Some of the others appear to be closed-end mutual funds which trade like shares of stock and seek long term capital appreciation, much like most other open-end funds do.